Impact pulverizer



NOV- 14, 1933' N. H. ANDREWS ET AL 1,935,344'

IMPACT 4PULVVERIZER Fi1ed June 16. 1931 e sheets-smet 1 WHW-ESS Bf frrTaR/vgr NOV- 14, 193.3-v .N. H.YANDREWS l-:r AL Y 1,935,344

IMPACT PULVERIZER Filed June 16, 19731` 6 sheets-sheet 2 INVENTOH VVITNE55 l NOW-14, l3933@ N. H. ANDREWS Erm. 1,935,344

IMPACT PULVERIZER Filed June 16. 1931 fr 6 Sheet/54511661: 3

IMIACT PULVERIZER 6 Sheets-Sheet 4` Filed June 16. 1951 WITNESS T ORNEY ,Nov 14, M533. N, H, ANDREWS E1' AL, @$935,344

IMPACT PULVERIZER 6 SheetsSheet 5 Filed June 16, 1931 HTTONEY MLM/U.

Nov. 14, 1933- N. H. ANDREWS T A1.` 1,935,344

IMPACT PULVERIZER Filed June 16, 1951 6 Sheets-Sheet 6 INVENTORS Patented Nov. 14, 1933 UNITED STATES IMPACT PULVERIZER,

Norwood H. Andrews, Moorestown, N. J., and

Walter J. Willoughby, Philadelphia, Pa., assignors to American Pulverizing Corporation, Camden, N. J., a corporation of New Jersey Application June 16, 1931. Serial No. 544,772

17 Claims.

Our invention relates to impact pulverizers, and more particularly to that type of pulverizer wherein two or more streams of stone, sand, coal, or other hard mineral are propelled against each other at a high velocity by jets of steam or compressed air, the impact of the pieces forming the streams being so great that the said pieces of mineral matter are shattered and reduced in part to a powder. Heretofore it has been deemed necessary to place the opposed mineral impelling jets in absolute'alinement and to maintain them in such alinement. This was difficult to accomplish, both `in the original installation of the jets and in maintaining them in alinement after the apparatus had been started to operate, due to the expansion of the parts under the heat of the steam delivered to the jets and due tothe abrasive action of the materials striking the exposed ends of the jet or material tubes. Whenever the jets were out of alinement then some other material impelled forwardlyat a high speed would not be met by an opposing stream of material and would strike against the wall of the pulverizing chamber or the head of the material tube and quickly abrade a hole through the wall or destroy the head of the material tube against which it strikes, thereby rapidly augmenting the lack oi alinement and often putting the machine completely out of commission.

The objects of the present invention are to overcome the objectionable features above referred to and to greatly increase efciency of the pulverizers of the impact type and to make it possible to pulverize material to a much greater degree of neness than has heretofore been possible.

A further object of this invention is to provide a construction in which the direction of 'the streams of material, under treatment, are unaffected by changes in temperature.

A further object of` this invention is to exclude as much as possible all air from the stream of l pulverized material leaving the pulverizing chamber, so that the powdered material is borne on a current of a vapor lighter`than air and which will not support and carry away particles as heavy, and consequently as large, as will oat in a current of air or of a mixture of steam and air.

A further object of this invention is to drive substantially all the material after impact out of the pulverizing chamber' by the steam delivered through the jets and to return the heavier insufliciently reduced particles by gravity back to the chamber in the apparatus whence the material is delivered to the jets, for retreatment and further pulverization.

A further object of this invention is to make the opening through the material tubes at the delivery ends thereof equal in diameter to the diameter to which the jet of steam has expanded when it reaches said delivery end of said tube. This makes it possible to use longer and larger material tubes and to provide a wide space between the jetsand the receiving end of the tubes thereby permitting of the treatment of larger pieces of material than have heretofore been successfully treated in this type of pulverizer.

A further object of this invention is to make possible the use of a series of three or more jets with their cooperating material tubes, or of an odd number of coacting jets disposed out of alinement with each other but equally spaced circularly from each other in the series and to cause the material delivered by one jet to be opposed by and impact against the material delivered from at least two other jets, thereby greatly increasing the number and kinds of impacts to which each piece of material is subjected.

A further object of this invention is to provide a bed of mineral, preferably like that being treated, in the pulverizing chamber and directly beneath the nozzles and beneath the focal point to which the jets are directed. During the operation of the device, the material which is impelled downwardly after the impact strikes with violence against this bed further pulverizing it and preventing the falling material from impinging directly against the walls of the housing and thereby preventing abrasion and wear to the apparatus.

A further object of our invention is to arrangel the jets and material tubes cooperating therewith in a plurality of series vertically disposed with respect to each other, whereby the jets in one series not only drives the material against opposing streams impelled by jets in the same series, but the jets of one series impels a part of the material, under treatment, against the streams or iiow of material impelled from the jets in the'other series, thereby subjecting each piece of material under treatment into repeated collisions with pieces striking it in many diiierent directions, with the result that the speed at which the material is reduced to a powder is greatly increased. l

Further objects of our invention will appear in i the specification and claims below.

In the drawings forming a part of this speci- 1w cation and in which the same parts are designated by like numerals throughout the drawings,

Fig. 1 is a vertical sectional view of a pulverizing apparatus embodying our invention;

Fig. 2 is a horizontal sectional view on the line Fig. 3 is a similar horizontal sectional view on the line 3-3 of Fig. 1;

Fig. 4 is a horizontal sectional view through a material tube showing its relation and disposition with respect to a steam jet and also showing, in a diagrammatic manner, the way in which the jets in one horizontal series interact with the other jets of the series and the material is driven from all the jets toward a focal point;

Fig. 5 is a somewhat similar diagrammatic view to show, in part, the interaction between the jets of two series of jets one above the other and why it is that from the point -of impact the material lies in the main upwardly from the upper side and downwardly from the lower side of the upper andlower series respectively, and the manner in which the steam from the jets drives all of the material, after impact, out of the impact chamber and upwardly through the delivery tube;

Fig. 6 is a vertical sectional view of a modified construction wherein the material tubes are omitted and openings are provided through the walls of the pulverizing chamber for the passage of the stream of steam and material impelled thereby; a construction particularly adapted for the pulverization of fine material, such as sand;

Fig. 'l is a horizontal sectional view on the line 7 7 of Fig. 6;

Fig. 8 is a diagrammatic view similar to Fig. 4, but wherein the circular spacing of the jets is not equal;

Fig. 9 is a similar diagram of an arrangement, wherein one nozzle is opposed by two and the circular spacing is n ot equal;

Fig. 10 is a fragmentary vertical sectional view of a modified baie for the delivery tube; and

Fig. 11 is a fragmentary vertical sectional view showing the uptake tube above the level of the material being treated when it is not necessary to exclude air from the uptake tube.

Referring first to the form of the invention illustrated in Figs. 1 to 3 of the drawings, the pulverizer consists of a circular steam header y1 which is provided with two steam chambers 2 and 3 which are preferably continuous circular passages within the header, preferably having no communication one with the other. Superheated steam, at high pressure, is delivered to the chamber 2 by a pipe 4 controlled by a valve 5 and steam is independently delivered to the chamber 3 by a pipe 6 and valve 7. To the inner side of the circular steam header 1 and respectively communicating with the chamber 2 is a circular series of five steam jets or nozzles 8, all directed to a focus at the center of the circular series, the jets of the series being circularly spaced equidistant from each other. The forward or dischargeend of each steam jet 8 projects slightly into and is in axial alinement with a material tube 9 respectively. Each material tube comprises a chuck l0 and a material nozzle 11 held in the chuck by a set screw 12.

The .upper half of the passage through the ring-like member 13 is preferably polygonal in horizontal cross-section, that is to say, when the Aapparatus is provided with five nozzles the inner surface of the upper part of the ring-like member 13 will preferably be pentagonal to provide flat faces against which the heads of the chucks 10 may lie at. The material tubes 9 of the upper series are preferably retained in position in the upper ring by set screws 15. Both the header 1 and the ring-like member 13 are supported on a stiff bottom plate 16 which is in turn supported on legs 17.

The header 1 is also provided with a second circular series of steam jets 8' which communicate with the steam chamber 3 and project inwardly from the inner wall of the header 1 to focus at the axial center of the impact chamber 14. These jets 8 are preferably located in a staggered relation with respect to the upper series of jets 8, that is to say, with their axes in a vertical plane midway between each pair of jets 8. Each jet 8' is similarly provided with a material tube 9' mounted in the ring-like member 13 and preferably held therein by set screws l5. The lower half of the impact chamber within which the material tubes 9 are mounted is also preferably pentagonal in shape, but in a staggered relationship with respect to the pentagonal upper portion.

The bottom plate 16 is preferably provided with a hole 18 which is preferably closed by a pan 19 bolted thereto, and which, in operation of the apparatus, remains full of loose material 19', as will be referred to again below.

Extending upwardly from the circular header 1 is a cylindrical housing 20 forming the outer wall of the material chamber 21 which, when the machine is operating, is filled with the material to be pulverized and into which raw material to be pulverized is continually fed. Near the upper end of the housing 20 we provide a ring 22 forming a seat and bearing for the edge of a circular distributing member 23, the periphery of which is provided with teeth 24 adapted to mesh with teeth of a driving pinion 25 mounted on a shaft 26 outside of the housing 20, the pinion passing through a slot 27 in the housing 20 to mesh with the teeth on the distributing member 23. This distributing member is more particularly shown in Fig. 2. It is provided with a circular series of openings 28 therethrough, one edge of each opening being provided with a vane 29 projecting downwardly into the material chamber.

The distributing member 23 also has a circular opening 30 fitting around the conical hood 3l, the upper end of which is attached to the upper end of the delivery tube 32 and the lower end of which is attached to the flange 33 at the bottom end of the delivery tube 32 and overlying the material tubes 9 of the upper series.

Above the distributing member 23 an inwardly and downwardly flaring iiange member 34 is preferably secured to the interior of the housing 20 to overlie the upper surface of the periphery of the distributing member 23 to prevent the material supplied to the apparatus from wearing the teeth 24 of the distributing member and of the pinion 25, by means of which the distributing member is slowly rotated. Arranged axially to the housing 2O and to the delivery tube 32 with its lower end open and extending downwardly into the upper open end of the housing 20 to a point in the material chamber just above the distributing member 23 and located between the delivery tube 32 and the housing 20, is a relatively large cylindrical uptakechamber 35 into which the material from the delivery tube 32 is discharged substantially horizontally after its impact against the baiiies 36 and 37 mounted on the upper end of the delivery tube 32. The uptake cylinder 35 may be supported in any suitable manner, as, for example, byA brackets 38 riveted to the sides of the uptake cylinder and to the top edge of the housing 20. The upper end 35 of the uptake chamber is preferably conical or frusta-conical terminating in a cylindrical throat 39 which in turn communicates with the lower end of the separator 40. The throat 39 is provided with a damper 41 by means'of which the ow of steam and dust from the uptake cylinder 35 into the separator 40 may be controlled.

Fresh raw material to be pulverlzed is supplied to the material chamber 21 from the chute 42 which discharges into the upper end of the housing 40 in the space between it and the outer surface of the uptake cylinder.

From the above description of the construction of our improved impact pulverizer, the operation will he more apparent.

Raw material is discharged into the housing 20 from the chute 42 and the'distributor member 23 is slowly rotated, driven by the pinion 25. The raw material falls' through the openings 28, the vanes 29 slowly agitate and distribute the material evenly throughout the material chamber and keep the mass moving slowly downwardly and the hood 31 directs the downward moving mass outwardly over the steam jets 8 and 8'. The apparatus is kept filled with raw material preferably to a. point near the top of the housing 21, that is to say, to a plane just below the end of the chute 42 as indicated by the dot-and-dash line 43. In this way the space between the lower'end of the uptake cylinder 35 and the cylindrical housing 20 is lled with and practically sealed by raw material to be pulverized. Some of it rises slightly into the lower end of the uptake cylinder. Such a position is `indicated by the dot-and-dash line 44, but the general direction of the material downwardly and even when the raw material is sand, it will not rise very much into the uptake cylinder 35.

But the material lling the chamber 21 will consist of a large proportion of nes and it will be effective to substantially seal the lower end of the uptake cylinder against the entry of air as will be referred to again below.

Referring now to Fig. 4, the material tubes 9 (or 9 in construction they are alike), are provided with Venturi tube bores 45 in axial aliney ment with the jet 8 (or 8 as the case may be) and the diameter of the bore 45 at the discharge end thereof, that is to say, nearest the focus 46 of the jets, is carefully calculated to be of the size to which the jet of steam 47a has expanded when it has reached the end of the material tube, as clearly shown in Fig. 4. This arrangement permits of the use of a much larger bore 45 through the material tubes with a faster treatment of a larger quantity of material in a given length of time and also the treatment of larger pieces. As the material is impelled toward the focus 46, it first engages the streams 47h and 47e striking them at the sides thereof and the eect of this is to drive the material of the stream 47a toward the focus 46.

The jet 47a is also opposed by the two jets 47c and 47d. V

The result of this is that the material after impact, follows, generally speaking, at rst oneI alined jets are employed. In those machines or apparatuses, the material ilies radially from the axis of the streams in all directions. But where there are more than two streams, equally spaced circularly from each other, the tendency of the material to fly radially disappears and the motion of the material after impact is substantially in two directions only, up and down. This is perhaps more readily understood by reference to Fig. 5 wherein we may consider as illustrative, the streams 47 and 47c oi' the upper series and the streams 47" and 47' of the lower series. After impact, the material from the streams 47 and 47 o1' the upper portions of the streams follows, in general, the lines 48, 48 above the axes of the streams and on the lower side or portion of the streams 47, and,47c, it flies downwardly but the downward motion at 49, 49 is opposed by the material rising from the upper portion of the streams 47a', 47' as indicated at 50, but the shattered material is naliy drawn upwardly as at 49' and 50 due to the large volume of steam filling the impact chamber from the lower series of steam jets 8' and finally discharging upwardly. Similarly, as indicated by the numeral 51, the material from the lower portion of the lower series of streams and as diagrammatically 'illustrated as streams 47a and 47 is impelled downwardly but striking against the bed of loose material 19 in the pan 19, it is swept and lifted by the rush of steam filling the pulverizing chamyber and is impelled upwardly around and between From the above discussion of Figs. 4 and 5,

it will be apparent that when steam is admitted to the steam chambers 2 and 3 byopening the valve 7 connected to a source of superheated steam at high pressure and the material is driven by the jets into the impact at the focal point of the pulverizing chamber, each piece of material is struck many times by other pieces oi material impelled thereagainst from the other jets with the result that an exceedingly rapid reduction of the material to a line condition is attained. The material traveling upwardly in the delivery tube 32, at high speed, strikes against the baffles 36 and 37 and is deected radially into the relatively large uptake cylinder 35, where the steam, expanding fills the uptake chamber 35 and moves upwardly at a substantially reduced speed to the upper part 35 of the uptake cylinder. Here, in the uptake cylinder 35, the particles which are too heavy to be carried in the rising streamrof steam and even the heavier particles of dust carried into the separator 40.

The dust or powder which is ne enough to be borne upwardly through the throat 39 into the separator 40 is there retreated as is usual in a separator and the heavier pieces which are stopped by the separator fall through the throat 39 into the uptake chamber and back to the top 44 of the material closing the end of the uptake cylinder `35, while the lighter materials are borne away out of the separator oating in the current of dry steam to a dust collector, not shown.

By making the steam header 1 circular and as a single casting and by mounting the steam jet nozzles 8 and 8 directed straight inwardly to the focal center 46, and by making the member 13 in which the material tubes 9 and 9' are mounted, ring-like, the expansion of the said members, under the influence of superheated steam at high pressure, is all radial with respect to the focal point 46. Even the longitudinal expansion of the jets 8 and 8 themselves is radial to the focus 46, with the result that the alinement of a jet or material tube with respect to the focal point 46 is never changed by the expansion or contraction of the parts.

In Figs. 6 and 7, is illustrated a modified form of our invention which can be used for the pulverization of a fine raw material such as sand. The construction is, in many respects, identical with that shown in Figs. 1 to 3 and where identical parts appear therein they are given the same numerals as those employed in describing the construction shown in Figs. 1 to 3.

'Ihe steam header 1 has but a single steam chamber 2 which is kept supplied with steam by pipe 4, also connected to a suitable source of superheated steam under high pressure. There is but a single circular series of steam nozzles 8, all directed to a single focal point 46 at the center of the apparatus. In this construction, the impact chamber 14' is at the lower end of the delivery tube 32. In fact, the lower end of the delivery tube 32 forms the walls of the impact chamber 14'. The bottom of the cylindrical housing is closed by the bottom plate 18 and below the impact chamber is the pan 19 which is kept filled with loose material 19 up to a predetermined level.

The distributor 23 is like the distributor previously described and is similarly mounted in the housing 20 to be driven by the pinion 25. Only the lower portion of the uptake cylinder 35 is illustrated, but the extent to which it enters the upper open end of the housing 20 is clearly indicated.

In this construction, the conical hood 31 and the material tubes 9 are not used for it has been found that in the treatment of finely divided mobile particles like particles of sand, the dry steam, at high pressure, will form for itself a clean passage or bore 45a through the sand if an opening 45b be provided in the walls of the impact chamber of a size suicient to permit the free ilow therethrough of the Vstream of steam and sand. In other respects, the operation of the device is like that of the form illustrated in Figs. l. to 3.

The jet of steam issuing from the nozzles 8 forms a tube or passage 45a through the sand to the openings 45b which are in diameter equal to the diameter to which the stream has expanded when it reaches the opening and continually drives a stream of san'd through the openings 45b into the impact with other similar streams at the -focus 46 at the center of the impact chamber 14.

For the same reasons as those discussed in connection with Figs. 4 and 5, the particles of sand immediately after the moment of impact will be carried either vertically upward or vertically downward, but the steam delivered in the impact chamber 14 from the jets or nozzles 8 will also be operative to finally drive all of the material upwardly out of the delivery tube 32 into the uptake cylinder 35 and to maintain a constant level of loose material 19 in the closure 19. The slow moving distributor 23 with its vanes 29 serves to keep the material rllling the material chamber 21, moving slowly downwardly into operative proximity to jets 8.

The material carried upwardly through the delivery ,tube 32 is engaged by a baille 37 and thrown thereby substantially radially into the uptake cylinder 35 in the same manner as that before described and a separation of the coarser particles from the dust is effected. In the drawings of this modification, the points or levels to which the sand iills the space between the housing 20 and the lower end of the uptake cylinder 35, is indicated by the dot-and-dash line 43 and the extent to which the sand might rise in the lower end of the uptake cylinder 35 is similarly indicated by the dot-and-dash line 44, thus more positively showing how it is that the material in the material chamber 21 eiectively seals the uptake cylinder 35 against the entry of air and how it is that the uptake cylinder 35 and the other pieces of apparatus into which the dust from the uptake cylinder is borne can be kept filled with substantially dry steam alone, the only air admixed therewith being that which may be contained in the sand between the particles thereof in the material chamber and consequently entrained with the steam as it impels the sand into the impact chamber.

The constructions and operations above' described may, however, be considerably modied without departing from the spirit and scope of the appended claims.

Thus while it is generally desirable to space the jets or nozzles 8 or 8 and the wearing tubes 9 or 9 of each circular series equidistant angularly from each other, it is not absolutely necessary or essential that they be so equally spaced. It is necessary that the material being treated be directed to a focal point or region in the pulverizing chamber and that the force of one stream of material, under treatment, be opposed and balanced by the force of the streams of material impelled against it. Every stream projected into the impact chamber must be disposed in such a manner as to be opposed and balanced by the opposing stream or streams.

Thus in Fig. 8 We have shown diagrammatically two streams 47a and 47b arranged in such a manner as to be opposed and balanced by the streams 47c and 47d, the streams being alike, but the spacing of the stream 47b from the stream 47c and of the stream 47a from 47d is greater than the angular spacing between the jets 47a and 47b on the one side and 47c and 47d on the other.

In Fig. 9 is diagrammatically shown and illustrated a further modification wherein the stream 47f is opposed by two jets 47c and 47d but the jet 47f must deliver as many pounds of steam in each unit of time as is delivered from the two jets 47c Iand'47d combined. This is readily effected by making the jet 47I and its wearing tube suiciently large to deliver the required amount of steam in the unit of time or by the independent regulation of the quantity of `steam delivered to and from each jet or nozzle by valves 52 so adjusted as to produce the required balance of force at the focus of the streams.

In the above description of' the construction, reference has been made to -the use of one more conical or frusto-conical deiiector 36, 37 or 37 at the upper end of the delivery tube 32. We have found that the velocity of the stream of materialbeing treated and steam in the delivery tubes 32 and 32 is so great that substantially all of the material under treatment will be blown laterally radially from the upper end of the delivery tube 32 even if the deector were made fiat as is indicated in Fig. 10. We contemplate taking advantage of these facts by utilizing a flat defiector 37 Yoi? hard steel or other hard material, such as iiint, against which the material coming from the deliveryv tube 32 is thrown with great force to contribute to the more rapid reduction of the material to an impalpable powder.

The bed `19 of sand or similar fine loose material serves to protect the bottom of the impact chambers 14, and 14 from the severe abrasive wear to which it would be subjected if it were closed by a metal plate located so closely to the axes of the jets of the stream of material being pulverized that no material could remain thereon. The layer or bed of fine loose hard material receives `the impact of the pieces of mineral after the impact of the streams together and prevents the fiying pieces from striking and abrading against a smooth metal or bottom to the impact chamber.

In the usual operation 'of the device, the pan 19 will be filled with the fines of the material which is being pulverized,-that is to say, when the material to be pulverized is delivered into the housing 20 and the apparatus is started by admitting steam to the jets, the pan 19 will soon ll up to a denite level with a fine material impelled therein by the jets and falling to the bottom after impact, but after this pan is filled up to that definite level, which is a point a little below the heads of the material tubes, as is indicated in Figs. 1 and 6, the pan remains filled with loose material. The level remains substantially unchanged. The material thereafter striking against this bed of loose material is carried away upwardly out of the tube 32 by the rapdlyupwardly moving column of steam from the impact chamber V14'. After the device has been operated for a time, the material 19 in the pan 19 stays there except that probably a slow pulverization of the particles forming the upper surface of the bed 19 may take place due to the impact against it of the material fiying downwardly from the jets. But whatever material is so pulverized'by such impact is quickly replaced by heavier particlesso that, except at the surface of the bed 19', the material in the pan is immobile during the operation of the device.

We contemplate, however, the utilization of this operation by initially filling the pan 19 with a material which is considerably harder than the material to be pulverized. -The impact of the pieces flying downwardly from the jets against the upper surface of this hard material 19 supplements the pulverization effected by the impact of the streams against each other by further shattering, pulverizing or` reducing the softer pieces striking the bed 19 of hard material.

We have also referred to the sealing of the lower end of the uptake tube by filling the.

housing 20 with the material to be treated and maintaining the level of the upper surfaces above the lower end of the uptake tube 35 as is most clearly illustrated in Fig. 6. This is the preferred manner of operating the device when the machine or apparatus is used for the mere pulverization of minerals in order that only the lightest almost impalpable grains resulting from the impact may be borne away in an atmosphere o; steam, the weight of which is less than that o air.

But when the device is used, for instance, for pulverizing anthracite coal, and the pulverized material is conducted directly to a furnace for combustion, the sealing of the lower end of the uptake tube 35 is not so desirable, for a considerable volume of air is required in the furnace to erect a combustion of the fuel. In such cases, therefore, we prefer to admit some air to the uptake tube 35 by either raising the lower end of the uptake tube to a point at or about the level 43 of the upper surface of the material in the material chamber as clearly shown in Fig. 11 in order that some air or a suflicient amount of air may be entrained through the mass of coal surrounding the lower end of the uptake tube 35 and may be drawn into the uptake tube through the said lower end, but when so operated, the quantity of air admitted should not be sufficient to cool and condense the steam in the uptake tube or in. the conduit, which conducts pulverized fuel to the furnace. regulated however by keeping the level 43 of the material in the housing 40 such that only the desired amount of air is entrained with the fuel into the lower end of the uptake tube 35.

Having thus described our invention, what we claim and desire to protect by Letters Patent of the 'United States is:

l. Inv an impact pulverizer, a circular series of jets, means to supply a gaseous iiuid underpres= sure to said jets, 'a relatively small impact chamber open at the top and closed on the sides and bottom and at the center of vwhich is a focal point to which all the jets of the series are directed, a bed of loose hard granular material covering the bottom of said impact chamber below the plane of said jets to protect the bottom of said impact chamber from abrasion by the material after impact, and a delivery tube of substantially the same diameter as that of said impact chamber and leading from the top of said chamber vertically upwardly and out of which all the material after impact is driven at high speed by the gaseous uid issuing from said impact chamber.

2. In an impact pulverizer, a circular series of jets, means to supply a gaseous fluid under pressure to said jets, an impact chamber at the center of which is a focal point to which all the jets of the series are directed, a bed of loose hard, granular material covering the bottom of said impact chamber below the plane of said jets, a delivery tube leading from the top of said chamber substantially vertically upwardly and through which all the material under treatment is driven after impact by the gaseous fiuid delivered from said jets, an uptake chamber into which all the material after impact is delivered from said delivery tube, and means to gravitationally return the pieces of material which are not suihciently reduced in size from said uptake chamber back to the rear of said material tubes for re-treat-i ment.

3. In an impact pulverizer, the combination of an annular header, a plurality. of jets, spaced from each other circularly and projecting in- This is easily wardly from the header and directed to a focal point, means to supply a gaseous fluid, under pressure, to said jets, a material tube for each jet in axial alinement with the jet, an annular member substantially concentric with said header and between said jets and said focal point, in which said material tubes are fixedly mounted, a housing extending upwardly from said header and a delivery tube extending upwardly rfrom 'said annular member, a closure for the underside of said annular header and spaced sufficiently below said focal point to retain a bed of hard loose material covering the bottom of said impact chamber to protect said bottom from the abrasive action of said material being pulverized, arl uptake cylinder of substantially greater diameter than said delivery tube and in axial alinement with said header and having its lower open end projecting into the upper open end of said housing between said housing and said delivery tube and into the lower open end of which said delivery tube discharges said gaseous fluid and material after impact, and means to feed raw material into the space between said uptake tube and said housing.

4. In an impact pulverizer, the combination of a circular header, a plurality of jets, spaced from each other circularly and projecting inwardly from the header and directed to a focal point, means to supply a gaseous fluid, under pressure, to said jets, a material tube for each jet in axial alinement with the jet, a circular member concentric with said header and between said jets and said focal point in which said material tubes are xedly mounted, a housing extending upwardly from said header to form a material chamber between said housing and said circular member and a delivery tube of substantially the same diameter as said circular member and extending vertically upwardly from the upper end of said circular member, a'closure for the underside of said circular header, spaced sufficiently below said focal point to support a bed of loose hard material for protecting the underside of said impact chamber from abrasion, an uptake cylinder in axial alinement with said header, said circular member and said delivery tube, said uptake having its lower end open and extending into the upper end of said housing between said housing and said delivery tube below the level of the material in said material chamber and into the lower end of which said delivery tube extends and discharges said gaseous fluid and material after impact; and means to feed raw material into the space between said uptake cyldinder and said housing.

5. In an impact pulverizer, a plurality of sets of jets spaced circularly, the sets of jets being parallel and arranged in a relatively vertical series, each set of jets being in a relatively horizontal plane and directed to a focal point coincident with the axis of said vertical series, an annular member having its axis coincident with the foci of all the series and forming an impact chamber, a material chamber surrounding said impact chamber, a delivery tube extending upwardly from one end of said annular member and communicating with said impact chamber, the other end of said impact chamber being closed, a separation chamber at a substantially higher level than said material chamber and into which said delivery tube discharges, the lower end of said separation chamber being above and in communication with said material chamber and discharging gravitationally the tailings from said separation chamber back to said material chamber, and means to deliver a gaseous fluid under pressure to said jets and to drive all the material after impact through said delivery tube.

6. In an impact pulverizer, a plurality of sets of jets spaced circularly and arranged in'a vertical parallel series, each set of jets being in a horizontal plane and directed to a focal point substantially coincident with the axis of said vertical series, a cylindricalmember having its axis coincident with the foci of all the series and forming an impact chamber, a material chamber surrounding said impact chamber, a delivery tube 7extendingupwardly from one end of said impact chamber, the other end of said impact chamber being closed, a separator substantially above said material chamber and operative to deliver said tailings gravitationally back to said material chamber, and means to deliver a gaseous fluid under pressure to each series of jets independently of the other series of jets.

7. In an impact pulverizer, the combination of a circular member forming an impact chamber,

a material chamber surrounding said impact chamber, a circular series of dry fluid jets in said material chamber and arranged to discharge to a focal point in said impact chamber to which said jets are directed, the number of jets in said series being more than two and angularly spaced from each other, onevend of said impact member being closed, a discharge tube communicating with the other end of said im'- pact chamber and through which substantially all material, after impact, is impelled and discharged as a stream4 by the force of the uid delivered from said jets, and a baiile of hard material at the delivery end of said tube and presenting a surface substantially normal to the axis of said delivery tube against which the material driven through said delivery tube strikes violently and is further shattered and from which said material is driven laterally after striking said baffle.

8. In an impact pulverizera plurality of sets of` dry fluid jets spaced circularly, the sets of jets being arranged in a relatively vertical series, the sets of jets being disposed in parallel relatively horizontal planes and the jets of each set being directed to a focal point substantially coincident with the axis of said vertical series, a member having anaxis substantially coincident with the foci of all the series of jets and forming an impact chamber, a delivery tube extending upwardly from the upper end of said member and communicating' at its lower end with said impact chamber, the bottom of said impact chamber being closed, means to deliver said dry fluid at high pressure to said jets, means to also deliver loose material to be pulver-ized to the stream of fluid issuing from said jets, a separation chamber surrounding the upper end of said delivery tube and a baffle of hard material projecting into the path of said material as it is discharged from said delivery tube and operative to further pulverize said material by impact and said delivery tube substantially at the level at which the raw material is delivered into said impact chamber, means to supply dry gaseous fluid at high pressure to said header to impel streams of raw material through said material tubes into impact at said focus in said impact chamber and to drive the material constituting said stream after impact vertically through said delivery tube and out of the end thereof laterally into said uptake tube or chamber.

l0; In an impact pulverizer, the combination of a casing providing. an impact chamber and a material chamber, a plurality of dry uid jets arranged in a substantially horizontal plane and directed to a focal region in said impact chamber to impel streams of material from said material chamber against each other to and at said focal region in said impact chamber, a conduit leading from said impact chamber in a direction substantially normal to the plane in which the axes of said jets liel and through which all of the material, both line and coarse, after impactis impelled as a stream by the expanding fluid from said jets after impact, said conduit extending to a point above the upper level of the material in said material chamber, and an uptake separation tube and chamber above said material chamber and into which the material from said conduit is discharged, in which the velocity of -said stream is reduced, and from which the tailings fall gravitationally into said material chamber.

l1. in an impact pulverizer, the combination of a lcasing providing an impact c hamber and a material chamber, a plurality of iiuid jets, the axes of which are in a common plane and which are operative tojmpel material at high velocity from said material chamber to a focal region in said impact chamber to which said axes are directed, a delivery tube through which all of the material, after impact, vis impelled at high'speed as a unidirectional stream, by the expanding fluid, means providing a hard substantially non-abra-v sive, non-wearing surface projecting into said stream and by which the said material impinging thereon is further shattered, and deflected laterally and an uptake cylinder substantially larger in diameJ er than said delivery tube into which said uid and material are delivered by said delivery tube, in which the speed of the iiuid is substantially reduced and the heavier insuilciently pulverized particles -are separated from the light insuiciently pulverized particles.

l2. 1n an impact pulverizer for comminuting hard loose material, the combination of a material chamber, an impact chamber substantially closed on its bottom and on its sides and open at its top end and positioned within said material chamber well below the level of the surface of the loose material in said material chamber to be treated, means to project relatively small streams of iuid moving with great `velocity through material in said material chamber to a focal region in said impact chamber below the level of the material under treatment in said chamber to impel streams of loose material from said material chamber intoimpact at said focal region in said impact chamber, the axes of said streams lying in a common substantially horizontal plane, `a separator chamber having its lower end open and terminating in said material chamber a little below the level of the material in said material chamber, a delivery tube communicating at its lower end with the upper end of said impact chamber and extending vertically upwardly through said material in said material chamber and terminating within said separaion chamber and through which all the material after impact, both pulverized and tailings, is impelled at a high speed by said iiuid and from the upper end of which it is discharged into the said material chamber, the heavier insuiiiciently pulverized tailings falling graviLationally in said separator chamber back into said material chamber for retreatment.

13. In an impact pulverizer, a circular series of jets, means to supply a gaseous uid, under pressure, to said jets, an impact chamber closed at the bottom and sides and open at the iop and at the center of which is a focal point to which all the jets of the series are directed, a delivery tube leading from the top of said chamber vertically upwardly and Jthrough which all the material under treatment is driven after impact by the iiuid issuing from said impact chamber, and an uptake cylinder of relatively large diameter into which all of the material and said uid is discharged from said delivery tube and in which the speed of the uid is greatly reduced.

le. In an impact pulverizer, a housing providing an impact chamber closed on the bottom and on the sides and open at the top, a circular series of more than two jets directed to a focal region in said impact chamber, means to supply a gaseous huid, under pressure, to said jets, a delivery tube of substantially the same diameter as said circular member and leading vertically upwardly from the top of said impact chamber' and through which all of the material after impact is driven at a high speed by and with the gaseous fluid from said impact chamber, and an uptake chamber surrounding the upper end of said delivery tube and into which the said material and the gaseous uid are discharged from said delivery tube, said housing providing a material chamber surrounding said impact chamber and into which said jets project, and means for supplying raw material to said material chamber, said uptake chamber constituting a separation chamber directly over said material chamber and from which the insuiciently pulverized particles gravitationally fall to the surface of the material in said material chamber for further pulverization.

15. In an impact pulverizer, the combination of an annular member forming the relatively vertical walls of an impact chamber, a material chamber surrounding said impact chamber, a circular series of jets in said material chamber arranged to discharge through said vertical walls of said impact chamber to a focal point in said impact chamber to which said jets are directed, the number of jets of the series being more than two and circularly spaced from each other, means to supply a gaseous fluid, under pressure, to said jets, one end of said impact chamber being closed,

and a discharge tube communicating with the other end of said impact vchamber and through which substantially all oi. the material after imchamber and of substantially larger diameter than said delivery tube into the lcwer open end of which said delivery tube discharges said gaseous uld and material from said impact chamber and in which the heavier insiifllciently pulverlzed particles are separated from the dust and fallA by gravity back into said material chamber.

16. In an impact pulverizer, thecombination of a circular member forming an impact chamber, a material chamber surrounding said impact chamber, a series of jets'in said material chamber and arranged to discharge to a focal point in said impact chamber'to which said :lets are directed, the bottom of said impact chamber being closed, means to supply a gaseous fluid, under pressure, to said jets, a discharge tube communicating with the upper end of said impact chamber and extending straight upwardly therefrom and through which substantially all of the gaseous fluid and material, after impact, are impelled and discharged by the force of the fluid delivered from said jets, and an uptake cylinder of substantially larger diameter than said discharge tube, the lower end of which extends into said material chamber, and into the lower end of which said discharge tube delivers said gaseous fluid and material after impact, said uptake cylinder forming a separator chamber in which the heavier particles are separated from the dust and fall gravitationally in said uptake cylinder to the upper surface of the material in said material chamber.

17. In an impact pulverizer, an impact chamber. a material chamber surrounding said impact chamber, a series of jets in said material chamber arranged to discharge to a focal point in said impact chamber to which said jets are directed, the bottom of said impact chamber being closed, means to supply a uid, 'under pressure, to said jets, a discharge tube communicating with said impact chamber and extending straight upwardly therefrom into which substantially all of the said fluid and the material, yafter impact, are impelled and discharged by the force of the fluid delivered from said jets, and an uptake cylinder of substantially larger diameter than said discharge tube into the lower end of which said discharge tube delivers said gaseous fluid and material, after impact, said uptake cylinder forming a separator chamber in which the tailings are separated from the finest particles and from which the coarser tailings are gravitationally returned tc said material chamber for retreatment.

^ NORWOOD H. ANDREWS.

WALTER J. WILLOUGHBY.' 

